Guaifenesin phenylephrine is a combination of two medications commonly found in many over-the-counter (OTC) cold and flu medications. Guaifenesin is an expectorant and works to loosen chest congestion. Phenylephrine is a decongestant and helps to relieve nasal stuffiness, sinus pressure and sinus congestion. These medications work together to relieve symptoms of the common cold and flu, including nasal congestion, coughs, runny nose, sneezing and sinus pressure.

Guaifenesin is an expectorant. Expectorants loosen and break up mucus in the chest, making it easier to expel it from your body; as a result, the air passageways are clearer and breathing becomes easier. Guaifenesin is also known as guaiphenesin and glyceryl guaiacolate. Guaifenesin is readily available over the counter in several name brands, as well as by prescription. It is sold as a single medication or in combination with other medications, such as phenylephrine or acetaminophen.

Phenylephrine is a decongestant. Decongestants work by shrinking the blood vessels in the nasal air passages. As a result, the nasal passages return to normal size and breathing becomes easier. Phenylephrine is also sold in nasal spray form.

Guaifenesin phenylephrine is taken orally and recommended for children and adults over 12 years of age. Some forms may be available for children between the ages of 6 and 12, though it is strongly advised to avoid giving any expectorants or decongestants to children under 6 years old. Pregnant and nursing moms should not take this medication, in any form, unless it is recommended by their physician. Guaifenesin phenylephrine should always be taken with a full glass of water and, if nausea is experienced while taking this medication, taking the medication after eating may help.

This medication combination is available in several forms, including tablets, capsules, time-release capsules, and liquid. Dosage depends on several factors, including the type and strength of the medication, and the age of the person taking it. Always follow package directions or your doctor’s instructions when taking this, or any, medication. Take only the recommended dosage and never take more than the directions advise. Follow the instructions for how often to take the medication and, if you miss a dose, skip it; do not take two doses at the next dose time.

Side effects of guaifenesin phenylephrine include nausea, dizziness and headaches. If you experience more serious side effects, such as fainting, shaking, seizures irregular heartbeat, trouble urinating, severe mood swings, or insomnia, consult with your physician immediately. Allergic reactions to guaifenesin phenylephrine are rare. Seek medical attention immediately if you suspect an allergic reaction. Symptoms of an allergic reaction include rash; itching; swelling of the mouth, throat and face; extreme dizziness; and difficulty breathing.

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